Adds new helper `content_settings_value`

This helper returns a value either from `content.settings` or from `options` hash.

What this brings?

You can now set essence view partial options in the `elements.yml` file:

```
- name: image
  contents:
  - name: image
    type: EssencePicture
    settings:
      image_size: '100x80'
```
EssencePicture#serialized_ingredient includes content settings

Take the content settings, defined in elements.yml, into account while generating the picture_url
Deprecate take_me_for_preview and rename it to as_element_title

The content definition has an option to mark it as element preview title. The option was named take_me_for_preview. This now is named as_element_title.
Fix handling of requesting unknown pages via api
Adds support for nested urlnames in pages api.
Allow latest versions of compass-rails and sass-rails

Fixes issues with apps using Rails 4.1 and compass image spriting
Adds a new rake task to import database dumps

These database dumps can be STDIN streams or from file.
Adds new capistrano task to export local data to remote

Like `cap alchemy:import[all,pictures,atachments,database]` you can now `cap alchemy:export[all,pictures,atachments,database]` to send local data to remote servers.
Escape the export db dump to be shell safe.